They call this a consensus?

"Only an insignificant fraction of scientists deny the global warming crisis. The time for debate is over. The science is settled."

So said Al Gore … in 1992. Amazingly, he made his claims despite much evidence of their falsity. A Gallup poll at the time reported that 53% of scientists actively involved in global climate research did not believe global warming had occurred; 30% weren't sure; and only 17% believed global warming had begun. Even a Greenpeace poll showed 47% of climatologists didn't think a runaway greenhouse effect was imminent; only 36% thought it possible and a mere 13% thought it probable.

Today, Al Gore is making the same claims of a scientific consensus, as do the United Nation's Intergovernmental Panel on Climate Change and hundreds of government agencies and environmental groups around the world. But the claims of a scientific consensus remain unsubstantiated. They have only become louder and more frequent.

More than six months ago, I began writing this series, The Deniers. When I began, I accepted the prevailing view that scientists overwhelmingly believe that climate change threatens the planet. I doubted only claims that the dissenters were either kooks on the margins of science or sell-outs in the pockets of the oil companies.

My series set out to profile the dissenters — those who deny that the science is settled on climate change — and to have their views heard. To demonstrate that dissent is credible, I chose high-ranking scientists at the world's premier scientific establishments. I considered stopping after writing six profiles, thinking I had made my point, but continued the series due to feedback from readers. I next planned to stop writing after 10 profiles, then 12, but the feedback increased. Now, after profiling more than 20 deniers, I do not know when I will stop — the list of distinguished scientists who question the IPCC grows daily, as does the number of emails I receive, many from scientists who express gratitude for my series.

Somewhere along the way, I stopped believing that a scientific consensus exists on climate change. Certainly there is no consensus at the very top echelons of scientists — the ranks from which I have been drawing my subjects — and certainly there is no consensus among astrophysicists and other solar scientists, several of whom I have profiled. If anything, the majority view among these subsets of the scientific community may run in the opposite direction. Not only do most of my interviewees either discount or disparage the conventional wisdom as represented by the IPCC, many say their peers generally consider it to have little or no credibility. In one case, a top scientist told me that, to his knowledge, no respected scientist in his field accepts the IPCC position.

What of the one claim that we hear over and over again, that 2,000 or 2,500 of the world's top scientists endorse the IPCC position? I asked the IPCC for their names, to gauge their views. "The 2,500 or so scientists you are referring to are reviewers from countries all over the world," the IPCC Secretariat responded. "The list with their names and contacts will be attached to future IPCC publications, which will hopefully be on-line in the second half of 2007."

An IPCC reviewer does not assess the IPCC's comprehensive findings. He might only review one small part of one study that later becomes one small input to the published IPCC report. Far from endorsing the IPCC reports, some reviewers, offended at what they considered a sham review process, have demanded that the IPCC remove their names from the list of reviewers. One even threatened legal action when the IPCC refused.

A great many scientists, without doubt, are four-square in their support of the IPCC. A great many others are not. A petition organized by the Oregon Institute of Science and Medicine between 1999 and 2001 claimed some 17,800 scientists in opposition to the Kyoto Protocol. A more recent indicator comes from the U.S.-based National Registry of Environmental Professionals, an accrediting organization whose 12,000 environmental practitioners have standing with U.S. government agencies such as the Environmental Protection Agency and the Department of Energy. In a November, 2006, survey of its members, it found that only 59% think human activities are largely responsible for the warming that has occurred, and only 39% make their priority the curbing of carbon emissions. And 71% believe the increase in hurricanes is likely natural, not easily attributed to human activities.

Such diversity of views is also present in the wider scientific community, as seen in the World Federation of Scientists, an organization formed during the Cold War to encourage dialogue among scientists to prevent nuclear catastrophe. The federation, which encompasses many of the world's most eminent scientists and today represents more than 10,000 scientists, now focuses on 15 "planetary emergencies," among them water, soil, food, medicine and biotechnology, and climatic changes. Within climatic changes, there are eight priorities, one being "Possible human influences on climate and on atmospheric composition and chemistry (e.g. increased greenhouse gases and tropospheric ozone)."

Man-made global warming deserves study, the World Federation of Scientists believes, but so do other serious climatic concerns. So do 14 other planetary emergencies. That seems about right. – Lawrence Solomon is executive director of Urban Renaissance Institute and Consumer Policy Institute, divisions of Energy Probe Research Foundation. Email: LawrenceSolomon@nextcity.com.